Immune Response In Multiple Sclerosis Research Articles

Identification of Epstein-Barr virus proteins as putative targets of the immune response in multiple sclerosis

MS is a chronic inflammatory and demyelinating disease of the CNS with as yet unknown etiology. A hallmark of this disease is the occurrence of oligoclonal IgG antibodies in the cerebrospinal fluid (CSF). To assess the specificity of these antibodies, we screened protein expression arrays containing 37,000 tagged proteins. The 2 most frequent MS-specific reactivities were further mapped to identify the underlying high-affinity epitopes. In both cases, we identified peptide sequences derived from EBV proteins expressed in latently infected cells. Immunoreactivities to these EBV proteins, BRRF2 and EBNA-1, were significantly higher in the serum and CSF of MS patients than in those of control donors. Oligoclonal CSF IgG from MS patients specifically bound both EBV proteins. Also, CD8(+) T cell responses to latent EBV proteins were higher in MS patients than in controls. In summary, these findings demonstrate an increased immune response to EBV in MS patients, which suggests that the virus plays an important role in the pathogenesis of disease.

Identification of Epstein-Barr virus proteins as putative targets of the immune response in multiple sclerosis

Identification of Epstein-Barr virus proteins as putative targets of the immune response in multiple sclerosis

Acinetobacter Immune Responses in Multiple Sclerosis

Multiple sclerosis (MS) is the most common cause of neurologic disability among young people. The etiology of MS is controversial, but immune responses are considered to somehow be involved. The diagnosis of MS depends on a combination of various clinical and laboratory features, but apart from some myelin-neuronal autoantibody profiles or oligoclonal bands in the cerebrospinal fluid no other serologic diagnostic test or marker has yet been discovered. However, the presence of antibodies to Acinetobacter species in MS patients opens the possibility of developing a composite laboratory diagnostic marker, the myelin-Acinetobacter-neurofilament index. Whether Acinetobacter is the triggering agent of MS remains to be determined, but the measurement of anti-Acinetobacter antibodies could be used as a marker of disease activity. To evaluate this, prospective randomized controlled studies should be performed with MS patients, especially in the early stages of the disease.

Mechanisms of Action for Treatments in??Multiple Sclerosis

The etiology of multiple sclerosis (MS) is incompletely understood, and evidence suggests there may be more than one underlying cause in this disorder. Furthermore, this complex and heterogeneous autoimmune disease shows a high degree of clinical variability between patients. Therefore, in the absence of a single therapeutic target for MS, it is difficult to apply conventional drug design strategies in the search for new treatments. We review the potential mechanisms of action of several effective therapies for MS that are currently available or in development. The effects of each treatment are described in terms of their actions on key processes in a five-step model of MS pathogenesis. Conventional immunosuppressants targeting intracellular ligands (e.g. mitoxantrone) have broad cytotoxic effects on B cells, T cells, and macrophages. This suppresses the pathogenic immune response in MS with high efficacy but is also associated with high toxicity, limiting the long-term use of these agents. Monoclonal antibodies (e.g. natalizumab and alemtuzumab) are a new generation of immunosuppressants that act on immune-cell surface ligands. These agents have narrower immunosuppressive actions and different safety profiles compared with conventional immunosuppressants. Immunomodulators (interferon-beta and glatiramer acetate), which shift the immune balance toward an anti-inflammatory response, are at the frontline of treatments for MS. Immunomodulators have targeted actions on the immune system, but affect a greater number of immunopathogenic processes than monoclonal antibodies. Given the inherent heterogeneity of MS, such treatments, which act at many levels of the disease, may achieve the best clinical results. Using our understanding of the interplay between mechanism of action and clinical effects in MS therapies may help us to better design and select new treatments for the future.

Oligodendrocyte apoptosis before immune attack in multiple sclerosis?

Barnett and Prineas1 recently reported new morphological findings in the brain of a 14-year-old patient with relapsing-remitting multiple sclerosis (MS) who died within 24 hours of the onset of a new symptomatic and fatal brainstem lesion. Within this early lesion, they observed extensive oligodendrocyte cell death which they attributed to apoptosis. Strikingly, no T lymphocytes were detected in the region of oligodendrocyte death. In an accompanying editorial, Trapp2 suggests that this finding indicates that the immune response in MS is not the cause of the oligodendrocyte cell death but is secondary to oligodendrocyte death caused by an unknown primary disease mechanism. Before accepting this interpretation, two points need to be considered. First, the patient reported by Barnett and Prineas received an intravenous injection of 100mg hydrocortisone.1 Corticosteroid administration reduces the number of T lymphocytes in the central nervous system in rats with experimental autoimmune encephalomyelitis (EAE).3 This commences as early as 4 hours after subcutaneous corticosteroid administration.3 A dose of 0.25mg dexamethasone/kg (equivalent to 6.7mg hydrocortisone/kg) inhibits the development of EAE by an effect on lymphocyte migration rather than by inducing T-lymphocyte apoptosis.4 Assuming a body weight of 50kg for the patient reported by Barnett and Prineas, the dose of hydrocortisone administered was 2mg/kg, which might have been sufficient to clear T lymphocytes from the central nervous system after these cells had induced oligodendrocyte death. Second, even in the absence of T lymphocytes, antioligodendrocyte antibody can induce oligodendrocyte death and consequent demyelination in the absence of complement and macrophages.5 Such a mechanism also needs to be considered in MS. Michael P. Pender MD, PhD*, * Neuroimmunology Research Centre, School of Medicine, The University of Queensland Department of Neurology, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.

Characterization of three human oligodendroglial cell lines as a model to study oligodendrocyte injury: morphology and oligodendrocyte-specific gene expression.

Oligodendrocytes, the myelin-forming cells of the central nervous system, are the target of pathogenic immune responses in multiple sclerosis. Primary cultures of human oligodendrocytes have been used to unravel the cellular and molecular mechanisms of immune-mediated injury of oligodendrocytes. However, these studies are hampered by the limited availability of viable human brain tissue. The present study was aimed at comparing the morphological and biochemical characteristics of the human oligodendroglial cell lines HOG, MO3.13 and KG-1C. We have determined oligodendrocyte-associated features of these lines and analyzed the degree to which they can be used as a model of human oligodendrocytes arrested at specific developmental stages. The oligodendroglial cell lines all exhibited markers of immature oligodendrocytes, such as CNPase and GalC, but not the astrocytic marker GFAP. Differentiation could be induced in HOG and MO3.13 cells, as was seen through a decrease in proliferation, an increase in process extension without formation of myelin sheets and up-regulation of genes associated with mature oligodendrocytes such as MBP and MOG. Microarray analysis revealed the expression of MAG, MOBP and OMG genes in HOG cells. The KG-1C cells displayed poor growth characteristics in the recommended conditions. In conclusion, our data show that the oligodendroglial cell lines HOG and MO3.13 can be used as a model of human oligodendrocytes "arrested" in an immature developmental stage. Culturing in appropriate medium can induce further differentiation of these cells. These cell lines can therefore be applied as a model to study immune-mediated injury of oligodendrocytes in relation to disease.

New concepts in the immunopathogenesis of multiple sclerosis.

Multiple sclerosis (MS) is a commonly occurring inflammatory and demyelinating neurological disease. It has been considered to be an autoimmune disorder mediated by CD4+ type 1 T helper cells, but recent studies have challenged this idea by indicating a role for other immune cells. So, T- and B-cell responses in the brain of patients with MS involve the clonal expansion of lymphocytes and the antigen-driven maturation of the B-cell receptors, indicating that the immune response in MS engages a broad range of immune cells that target a limited number of brain antigens. At variance with the classical view, axons are not spared during the inflammatory process. Indeed, axonal damage determines clinical outcome to a large extent. Studies of the mechanisms of axonal damage and neurodegeneration in MS are in their infancy. Here, we summarize recent advances in our understanding of the pathogenesis of MS, and conclude with an outlook on how to capitalize on this knowledge to develop new therapeutic approaches.

IL-18 is linked to raised IFN-γ in multiple sclerosis and is induced by activated CD4 + T cells via CD40–CD40 ligand interactions

We investigated T cell receptor induced IL-18 secretion, the cellular and molecular mechanisms associated with the induction of IL-18 and the role of IL-18 in IFN-γ production in the different stages of multiple sclerosis (MS). We found that anti-CD3/CD28 induced IL-18 production by peripheral blood mononuclear cells was increased in both relapsing–remitting and secondary progressive MS. In controls and relapsing–remitting MS neutralizing anti-IL-12 and anti-IL-18 alone equally suppressed IFN-γ production whereas in progressive MS, maximum suppression of IFN-γ was only observed when neutralizing anti-IL-12 and anti-IL-18 were given together, suggesting that in progressive MS, IL-12 and IL-18 function in a non-linked manner to induce IFN-γ. Elevated IL-18 production in MS was dependent on the interaction of antigen presenting cells with activated CD4 + T cells via CD40–CD40 ligand and the levels of IL-18 correlated with disease duration in secondary progressive MS. These results demonstrated that IL-18 has an important role in augmenting Th-1 type immune responses in MS and may be involved in immune changes that occur when patients enter the progressive stage.

Autoreactive IgG to intracellular proteins in sera of MS patients

IgG binding to multiple protein constituents in lysates of Jurkat cells was detected by Western blot in sera of patients with multiple sclerosis (MS) and systemic lupus erythematosus (SLE). The distribution patterns of bands with sera tested against protein lysates from normal Jurkat cells or from Jurkat cells exposed to apoptosis or oxidative stress inducing conditions were similar in most patients, but with inter-individual differences. The number of bands with sera of both patient populations far exceeded those (0 or 2 bands) detected with sera of healthy controls. Proteinase K, RNase and DNase pre-treatment of cell lysates suggested a protein nature for all of the antigens and a ribonucleoprotein (RNP) nature for some of the antigens recognized by serum IgG of MS and SLE patients. Only two MS patients had positive anti-nuclear antibody (ANA) titers, while all of them had positive Western blots. In addition to similarities, dissimilarities were also recognized between the humoral immune responses in MS and SLE. No IgG molecules were detected against phosphorylated proteins in the sera of MS patients, while multiple phosphoproteins were recognized by IgG molecules of SLE patients in immunoprecipitation experiments. These data suggest that in addition to ANA, the sera of MS patients contain autoantibodies directed against multiple intracellular proteins. The protein recognition patterns of immunoglobulins in MS share similarities, but also have distinct features when compared to those in SLE. The biological significance of these autoantibodies in MS remains to be understood.

Serum interleukin-12 levels in patients with multiple sclerosis

Increasing body of evidence which suggests a crucial role for interleukin (IL)-12 in modulating immune responses in multiple sclerosis (MS) prompted us to analyze IL-12 in serum from MS patients. We measured the sera concentrations of IL-12, tumor necrosis factor (TNF)- α and transforming growth factor- β1, in 21 MS patients and 13 patients with non-inflammatory nervous diseases. In clinically active MS, serum levels of IL-12 were detectable in 53% and TNF- α in 40% of patients. None of the patients with clinically inactive MS had detectable IL-12 and TNF- α sera levels. Analysis of serum concentrations of all three cytokines revealed no significant differences between MS patients and controls. These findings provide further evidence that both IL-12 and TNF- α might have an active role in immunopathogenesis of MS.

The intrathecal, polyspecific and oligoclonal immune response in multiple sclerosis.

We report an extended set of neuroimmunological data detected in cerebrospinal fluid (CSF) from n = 267 patients with definite multiple sclerosis (MS). Known frequencies of oligoclonal IgG (98%), frequencies of intrathecal fractions of IgG, IgA and IgM (72%, 9% and 20%, respectively) were confirmed and quantitated as intrathecal fractions, IgIF or CSF concentrations, IgLOC. Eighty-nine per cent of the patients had a combined 'MRZ-reaction', i.e. intrathecal antibody synthesis (Antibody Index, AI > 1.4) against measles, rubella and/or varicella zoster virus. Frequencies of single antibodies decreased from measles (78%) to rubella (60%), VZV (55%) and HSV (28%). This MRZ-reaction, indicating a chronic autoimmune type disease already at time of first clinical symptoms, is less sensitive but more specific than detection of oligoclonal IgG. With increasing intrathecal IgG synthesis the number of different locally synthesized antibody species were increased as well as the amount per species (increased mean AI values). The concentration of MRZ antibodies in CSF represents together about 2% of intrathecally synthesized total IgG. But, as a very particular result the ratio of intrathecally synthesized specific antibody/intrathecally synthesized JgG was 5-fold higher (0.24-0.85%) compared to the corresponding ratio in blood (0.06-0.17%) of MS patients. This difference between brain ratio and blood ratio is discussed to be indicative for the anti-MRZ antibody forming B-lymphocyte subset in blood migrating into brain at earlier time of pathophysiological start of disease. These results give a concise explanation of neuroimmunological aspects in MS, not understood so far.

Interleukin-12 and perforin mRNA expression is augmented in blood mononuclear cells in multiple sclerosis.

Cytokines are suggested to orchestrate an abnormal immune response in multiple sclerosis (MS). The regulatory cytokine interleukin (IL)-12 induces T-helper (Th) cell switch to the Th1 type and the production by cytotoxic T cells of perforin, a cell lysis-inducing factor. It has been suggested that Th1-like cytokines may promote the development of MS, and the production of perforin to induce oligodendrocyte damage. In-situ hybridization with radiolabelled synthetic oligonucleotide probes was used to detect and enumerate mononuclear cells (MNC) expressing IL-12 and perforin mRNA in blood and cerebrospinal fluid (CSF) from patients with MS and controls. Plasma and CSF levels of IL-12 (p70) were evaluated by ELISA. Higher numbers of IL-12 and perforin mRNA-expressing MNC were registered in blood in MS and also in controls with aseptic meningoencephalitis (AM) compared to healthy subjects. There were a few patients with other non-inflammatory neurological diseases who also had high levels of IL-12 or perforin mRNA expressing blood MNC. A parallel elevation was observed for IL-12 (p70) concentrations in plasma. In the MS patients' CSF, there was a further augmentation of IL-12 mRNA expressing MNC. To evaluate autoantigen-induced IL-12 and perforin mRNA expression, blood MNC were cultivated +/- myelin basic protein (MBP), a candidate autoantigen in MS. Higher numbers of MBP-reactive IL-12 and perforin mRNA expressing blood MNC were detected in MS than controls. The augmentation of both IL-12 and perforin in MS might reflect ongoing inflammatory processes in MS and could represent targets for future treatments.

The intrathecal, polyspecific and oligoclonal immune response in multiple sclerosis

The intrathecal, polyspecific and oligoclonal immune response in multiple sclerosis

Modulation of the immune response in multiple sclerosis: production of monoclonal antibodies specific to HLA/myelin basic protein.

Monoclonal Abs to the complex formed between human MHC class II molecules (DR7 and DRw11) and myelin basic protein (MBP) were produced. The specificity of these Abs was established by both FACS analysis and complement-mediated cytotoxicity of MBP- or OVA-pulsed human APC of the same or of different DR restriction. These Abs bound to and lysed only MBP-pulsed human APC of the same DR restriction (DR7 or DRw11) but not to APC of different DR restriction or pulsed with a different Ag (OVA). The physiologic role of these Abs was further investigated. They blocked the in vitro proliferative response to MBP-specific T cell clones isolated from multiple sclerosis patients in an antigen-specific and DR-restricted manner. However, the Abs did not affect the response of MBP-specific T cell clones of other DR restriction nor did they interfere with the response to other Ags (purified protein derivative or copolymer 1) presented on APC with the same DR restriction. These Abs may be useful for treating multiple sclerosis in which reactivity to MBP is implicated. Moreover, this approach may be extended to other autoantigens and their counterpart autoimmune diseases.

Cytokine secretion by multiple sclerosis monocytes. Relationship to disease activity.

Autoantigen recognition by specific T cells may initiate a tissue-specific immune response in multiple sclerosis (MS), which is a chronic inflammatory demyelinating disorder. During subsequent nonspecific immune amplification, interleukin 1 beta and tumor necrosis factor alpha are released by cells of the monocyte/macrophage lineage, with the potential to influence profoundly immune regulation systemically or within the central nervous system. Regulation of monocyte inflammatory gene expression may be relevant to the pathogenesis of MS. We investigated spontaneous secretion of interleukin 1 beta, tumor necrosis factor alpha, and prostaglandin E2 with the use of monocytes that we isolated from patients with active (n = 9) and stable (n = 9) MS and from age-matched normal controls (n = 9). The patient groups with MS were matched for age, duration of MS, and disease severity. Patients with active disease were within weeks of the onset of a clinical exacerbation. Monocytes were isolated by density gradient centrifugation, followed by adherence to plastic tissue culture flasks, resulting in a highly purified adherent monocyte preparation. Monocytes from patients with active disease spontaneously secreted less tumor necrosis factor alpha and less prostaglandin E2 compared with that in patients with stable MS, while interleukin 1 beta levels were below the level of assay sensitivity. Levels of interleukin 1 beta and tumor necrosis factor alpha increased to similar levels in response to lipopolysaccharide (0.1 mg/L), indicating that altered cell viability could not account for the observed differences. In response to lipopolysaccharide, prostaglandin E2 levels increased more significantly in patients with stable than active MS, suggesting differential sensitivity to stimuli of arachidonic acid metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular and humoral immune responses in multiple sclerosis

Cellular and humoral immune responses in multiple sclerosis

Cellular and humoral immune responses in multiple sclerosis

Cellular and humoral immune responses in multiple sclerosis

The intrathecal immune response in multiple sclerosis: A different concept of ‘specificity’

A hypothesis is presented in which the immune response in multiple sclerosis is conceived as a primary response to an autoantigen located within the immune system (e.g. a certain allotype or HLA epitope) which shows subsequent or simultaneous activity to a greater number of nominal antigens. The increased specificity for such antibodies to self-aggregation might play a critical role in the pathogenesis.

Temporal invariance and clonal uniformity of brain and cerebrospinal IgG, IgA, and IgM in multiple sclerosis.

Elevated cerebrospinal fluid (CSF) IgG and oligoclonal IgG bands on electrophoresis are valuable clinical markers for B cell proliferation in the brains of patients with multiple sclerosis (MS). Using two-dimensional electrophoresis, (2DE) we have established that the humoral immune response in MS brain is characterized by finite clonal complexity for the major Ig classes. An important question is whether this immune response is clonally stable or varies with time, related to the development of new lesions and random entry of B cells into the MS brain. To investigate this, we performed serial electrophoretic studies on CSF obtained from 19 patients with MS; the intervals ranged from 7 to 12 yr, with a mean of 8 yr. These analyses included studies of IgG, IgA, and IgM, and revealed that the humoral immune response in MS is clonally stable over long periods. Spontaneous fluctuations or reduction in CSF IgG levels by drugs did not qualitatively affect B cell clonal proliferation in MS brain, in that dominant bands and spots were not obliterated. It has been asserted that IgG synthesis in MS is nonsense antibody because the spectotypes of IgG isolated from different regions of MS brains differ. Factors other than clonal heterogeneity could account for differences found using one-dimensional analysis. B cell clonal products resolve into unique and well-resolved spots by 2DE; the method is uniquely suitable for analysis of restricted immune responses. Therefore, Ig were isolated from 11 regions of three MS brains and the 2DE patterns were compared. The similarity of the 2DE patterns indicate unequivocally that major clones are distributed uniformly although some clones are more prominent in some brain areas. IgA and IgM isolated from the same areas also showed similar patterns. Furthermore, the patterns of light and heavy chains in brain regions differed from serum but were similar to the autologous CSF, providing new evidence that CSF IgG in MS derives from synthesis in situ. Our results indicate that, once initiated, B cell clonal proliferation persists indefinitely and is little altered qualitatively at a clonal level over time, even when CSF IgG levels change or are altered by drugs. Our results are consistent with allotype and idiotype analysis of Ig production in MS and conflict with nonsense antibody proposals of the origin and nature of in situ synthesized Ig in MS.

Local and systemic immune response in multiple sclerosis: analysis of CSF inflammatory changes and peripheral blood T-cell subsets.

In order to investigate the significance of the immune response in multiple sclerosis (MS), we have compared changes in peripheral blood T-cell subsets to the cellular and humoral responses in the cerebrospinal fluid. Using monoclonal antibodies defining the Leu-3a and Leu-2a phenotypes, we found a highly significant (2P less than 0.001) increase of the Leu-3a/Leu-2a cell ratio in peripheral blood T-cells of multiple sclerosis patients with disease activity (acute phase or progressive form), while patients with inactive disease did not differ from controls. No characteristic alterations in the CSF inflammatory response could be correlated with changes in T-cell subsets in the peripheral blood. There was no significant difference in the cerebrospinal fluid cell count or the mean IgG index between patients with high or low Leu-3a/Leu-2a cell ratios. We conclude that increased CSF IgG synthesis in MS is probably not a direct consequence of the apparent reduction of Leu-2a positive cells in the peripheral blood. Thus the biological significance of the change in immunoregulatory cells in the blood of multiple sclerosis patients remains unknown.